Direct Access Archive
Filename extension .daa
Developed by PowerISO Computing, Inc.
Type of format Disk image

Direct Access Archive, or DAA, is a proprietary file format developed by PowerISO Computing for disk image files. The format supports features such as compression, password protection, and splitting to multiple volumes. Popular Windows disk image mounting programs such as Alcohol 120% and Daemon Tools currently do not support the mounting of DAA images; Linux and BSD also do not support mounting these kind of images.

Currently there is no published information about the format. Among mainstream applications, it can be opened or converted with PowerISO, MagicISO, AnyToISO and UltraISO. Various free open source packages are also available to convert DAA to ISO images.

File Structure

Although lacking official documentation, DAA image files are zlib- or lzma-compressed ISO images chunk by chunk.[1]


PowerISO provides free command-line tools for Linux and Mac OS X which allow the user to extract DAA files or convert them into ISO format, however these tools haven't been updated to support the newest version of the DAA format. The PowerISO Windows trial version only supports converting images from DAA files up to 300MB,[2] less than half of the capacity of a standard CD.

AcetoneISO is a free CD/DVD management application for Linux that can convert DAA to ISO with the help of the external PowerISO command-line tool for Linux.

daa2iso[3] is an open source command line application has been developed to convert DAA files to ISO files. The program comes with a Windows binary and source code which compiles under Unix-like operating systems. daa2iso allows users to select the .daa file, and the location for the .iso output via standard windows open and save dialogs.

For Mac OS X, DAA Converter[4] is a GUI application which wraps the daa2iso command-line tool (GNU license).


Due to using freely available compression algorithms, DAA includes the following features that are absent in ISO (but can be obtained by manually compressing ISO files):

  • Ability to compress images, thus saving space and allowing smaller downloads
  • Can be password protected
  • Can be split into multiple smaller files

External links

  • PowerISO Website

ISO conversion utilities

  • daa2iso application for Windows (source code included, and may be compiled for *nix / MacOSX without modification)
  • DAA Converter for Mac OS X, graphical Mac interface for daa2iso


This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.